1. Field of the Invention
The present invention relates to an assembly for securing an additional wheel (called a "dual" or "auxiliary" wheel) to the existing drive wheel of a tractor (called the "primary" wheel or, simply the "tractor wheel") in order to provide additional traction.
Dual wheel assemblies for agricultural tractors are common, and they may be classified, in general, into rim-mounted dual wheels or axle-mounted dual wheels. The present invention relates to a rim-mounted dual wheel wherein the rim of the dual wheel is mounted to the tractor wheel by means of bolt fasteners.
2. Known Constructions
In earlier dual wheel assemblies, individual brackets were welded on the rim of the dual wheel, and studs on the primary wheel were provided with eye-nuts. A long, hooked bolt fastener was then used to connect the eye-nuts to the brackets on the rim of the dual wheel, thereby securing the dual wheel to the primary tractor wheel.
Because of the weight of the dual wheel and the need to align the brackets on the dual rim with the eye-nuts on the tractor wheel, systems were devised, such as that disclosed in the Peterson U.S. Pat. Nos. 3,337,270, and my patent 3,736,029, which employ a track or rail extending about the interior of the rim of the dual wheel. In this type of construction, a movable bracket may be placed along the rim and located adjacent an eye-nut for fastening without having to align the rim of the dual wheel with that of the tractor wheel. Further, in my U.S. Pat. No. 3,736,029, there is disclosed a system for offset alignment of the bolt fasteners. The term "offset alignment" means that some of the bolt fasteners are connected to the dual wheel rim at a position located clockwise relative to their associated eye-nuts, while others are connected at locations displaced counterclockwise from their associated eye-nuts. This has the advantage that at least some of the bolts are always under tension whether the tractor is moving in a forward direction or in reverse.
Modern tractors have gone to engines of higher and higher horsepower, and the force necessary to secure a dual wheel to a tractor wheel has correspondingly increased. One of the problems with a rail-type dual wheel is that failures occur at the location where the rail is welded to the rim, due to the larger forces required to fasten the two together and the extreme conditions of use. This problem is aggravated with tractors of greater horsepower.
Further, it has been suggested by illustration in U.S. Pat. No. 3,836,202 that the fasteners might be aligned radially of the axis of the drive shaft in a rim-type of dual wheel system. This is useful in accommodating a single dual wheel to drive wheels having different spacings of eye-nuts.